Many agricultural implement frames include tubular members welded or connected together by brackets. The joints are subjected to very high loads and stresses.
Tube over tube connections for an implement frame construction typically employ one of two methods of construction. The first method includes welding the top and bottom tubes directly together using flare bevel welds. The direct weld procedure requires joint welds in hard to reach positions. If welds are required around tube corners, robotic welding techniques often are not used since programming the robot to closely follow the corners is not always possible. Fatigue and less than optimum load transfer characteristics of some joints can result in a weakened frame. The second method of frame construction uses gusset plates vertically extending between the top and bottom tubes and welded to the tubes. The weld positioning is better using the gusset method than the direct tube to tube weld method, but gusset weld methods often result in a joint with a lower fatigue life compared to other types of joints.
A further method involves tube through tube construction such as shown and described in commonly assigned U.S. Pat. No. 6,016,877. Such construction provides excellent frame tube joints and a very strong overall frame without need for extensive fixturing during manufacture, but such joints require laser cut apertures through tubes and are relatively expensive to produce. In addition, welding tube ends to adjoining tubes in the same plane continues to be a source of difficulty.